Electrical generators/motors commonly include rotors having shafts for supporting a central relatively large diameter cylindrical body which contains conductive windings which may, for example, produce magnetic flux which in turn produces stator current and voltage. Such windings are typically carried in a series of longitudinal slots that are cut or otherwise formed in the outer periphery and extend radially inwardly, as well as extending along the length of the rotor body. These windings are retained in the slots through the use of dovetail shaped wedges extending along the length of the rotor body through the use of complementary shaped dovetail grooves included within each of the aforementioned slots.
The portion of a winding contained in a longitudinal slot is interconnected to a similar longitudinal portion of another slot by way of an end turn portion which extends beyond the end of the relatively large diameter cylindrical rotor body. At operating speeds of 3600 rpm, for example, rather high centrifugal forces are exerted on the windings. In a conventional such environment the slot wedges restrain the longitudinal portions of the windings against such centrifugal forces and retaining rings attached around a circumferential lip at the ends of a rotor body are conventionally utilized to enclose and restrain the winding end portions against movement in the radially outward direction when the windings are subjected to such centrifugal forces. The retaining rings may be attached to the rotor body by way of shrink fit and other techniques. Some movement of the winding end turns nevertheless occur due to speed and temperature changes of the rotor, as well as the shrink fit nature of the retaining rings.
Current carrying connections to the rotor windings are necessary in order to apply field current to such windings in a generator, for example. Such connections are conventionally made from "bore copper" which may, for example, be an insulated conductor embedded in a number of ways in the rotor shafts which additionally may include slip rings connected to an exciter, for example. Since, as previously noted, speed and temperature changes may cause the end turns of the rotor windings to move both radially and axially, the connections, as well as the windings, are subject to centrifugal forces at operating speeds. Connector designs present formidable problems. For example, as will be appreciated by the artisan, such connectors in addition to being of appropriate size and material to meet current carrying requirements must also be sufficiently flexible to accommodate the noted coil movements and yet be sufficiently rigid to withstand centrifugal forces developed at operating speeds. Accordingly, an appropriate balance must be struck between these contrary requirements in order to avoid premature failures of the main lead connectors which due to the nature and location of such connectors would add significantly to repair costs.
We have discovered a connector design exhibiting the desired degrees of flexibility and rigidity as to be unaffected by relative movement between a winding end turn and a terminal stud associated with the rotor shaft.
Our main lead connector includes first and second conductive members each having a "T" profile. The central portions of these members are substantially coaxial with the tops of the two "T" profiles facing each other. Interconnecting these conductive members are two relatively thin bands of conductive material that are joined to one conductive member on opposite peripheral sides approximately midway along the central leg of the "T" and joined to the other conductive member at the ends of the side legs.
These flexible conductive bands are formed so as to have a portion positioned along the sides of the second conductive member central leg portion, as well as along the lower surface of each side leg. Thus formed, the "T" shaped second conductive member forms a support cap which restrains the flexible band members from movement in the radially outward direction when subjected to centrifugal forces present when the rotor is operating.
Thus, it is an objective of the disclosed main lead connector to avoid premature failure by designing the connector to be sufficiently flexible as to accommodate winding end turn movement associated with rotor temperature and speed changes but, nevertheless, rigid enough in design such that the connector elements can withstand centrifugal forces developed at operating speeds.
These and other objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.